<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			.mo{
				width: 100px;
				height: 100px;
				background-color: #00FFFF;
				transition: width 2s;
			}
			.mo:hover{
				width: 300px;
			}
			
		</style>
	</head>
	<body>
		<div class="mo"></div>
	</body>
</html>
